Apparatus for taking a continuous x-ray picture of the dental arch

ABSTRACT

An apparatus for taking a continuous X-ray picture of the dental arch, wherein the X-ray tube and the film are moved together in such a manner that the line connecting them crosses an ellipse approximating the dental arch of a patient, always making a right angle with a line tangent to the ellipse, without disturbing the relative position of the X-ray tube and the film. The shape of the ellipse can be changed in accordance with the shape of the dental arch of each individual patient to be photographed.

United States Patent n91 Kataoka et al.

[ APPARATUS FOR TAKING A CONTINUOUS X-RAY PICTURE OF THE DENTAL ARCH[75] Inventors: Kenzo Kataoka; Kazuo I-Iozumi,

both of Kyoto, Japan [73] Assignee: Kabushiki Kaisha Monita Seisakusho,Kyoto, Japan 22 Filed: Mar. 20, 1972 i [21] App]. No.: 236,119

Related US. Application Data [63] Continuation-in-part of Ser. No.96,890, Dec. 10,

l970, abandoned.

[52] US. Cl 250/490, 250/445, 250/479,

250/491 [51] Int. Cl. G03b 41/16 [58] Field of Search 250/50, 61.5, 65R, 70

[56] References Cited UNITED STATES PATENTS Faude et al. 250/6l.5

[451 Apr. 23, 1974 Moss 250/6l.5

Primary ExaminerWilliam F. Lindquist Attorney, Agent, orFirm-Christensen, OConnor, Garrison & Havelka [5 7] ABSTRACT Anapparatus for taking a continuous X-ray picture of the dental arch,wherein the X-ray tube and the film are moved together in such a mannerthat the line connecting them crosses an ellipse approximating thedental arch of a patient, always making a right angle with a linetangent to the ellipse, without disturbing the relative position of theX-ray tube and the film. The shape of the ellipse can be changed inaccordance with the shape of the dental arch of each individual patientto be photographed.

10 Claims, 7 Drawing Figures PATENTED APR 2 3 197% 3.8053732 SHEET 3 OF4 APPARATUS FOR TAKING A CONTINUOUS X-RAY PICTURE OF THE DENTAL ARCHRELATED APPLICATION This application is a continuation-in-part of ourcopending application Ser. No. 96,890, filed Dec. 10, 1970 under thetitle APPARATUS FOR TAKING A CONTINUOUS X-RAY PICTURE OF A DENTAL ARCH,and now abandoned.

BACKGROUND OF THE INVENTION INCLUDING CERTAIN OBJECTS THEREOF Thisinvention relates to improvements in an apparatus for taking X-raypictures of the dental arch of a human being, wherein the X-ray tube andthe film are moved along the dental arch of the patient so as to takenecessary X-ray pictures thereof.

For dental diagnosis and treatment it is necessary to know the relationbetween the teeth constituting the dental arch of the patient. To thisend, it is desired to take a continuous X-ray picture of the dental archas a whole. For taking such a continuous X-ray picture, it is requiredto move both the X-ray tube and the film together along the dental archof a patient without substantially disturbing the relative position ofthe tube and the film, and the movement must be continuous and smooth.What is more important is that the tube and the film must be moved, withthe straight line connecting them always perpendicularly crossing a linetangent to the dental arch at a point thereof whose adjacent area is tobe photographed. Unless the above straight line makes a right angle withthe tangential line, it will become impossible to take a picture of theobject at a position directly opposite thereto, and if the angle betweenthe two lines varies as the X-ray tube and the film are moved together,each area of the dental arch is photographed at a different angle sothat it will become of little use to have a continuous picture of thedental arch.

An apparatus which meets the above requirement has been proposed in anapplication filed simultaneously with the above copending application.In practice, however, the shape of the dental arch considerably differsin different individuals, so that in order to take an accuratecontinuous picture of the dental arch, it is necessary to change theshape of the ellipse along which the X-ray tube and the film are movedin accordance with the shape of the dental arch of each particularpatient to be photographed.

Accordingly, the primary object of the invention is to provide anapparatus for taking an accurate, continuous X-ray picture of the dentalarch regardless of difference in the shape thereof between differentpatients.

SUMMARY OF THE INVENTION The apparatus of the invention is based on thefact that the dental arch approximates an arc of a geometrical ellipseeven though it more or less differs in different persons. Therefore, thearrangement is such that the X-ray tube and the film are moved togetheralong the arcuate path of an ellipse approximating the dental arch, andat any position of their movement the straight line connecting the X-raytube and the film always makes a right angle with a line tangent to theellipse at a point where the connecting line crosses the ellipse.

The shape of the ellipse is varied with the shape of the dental arch ofeach individual patient. In practice, since the shape of the dental archgenerally corresponds to that of the jaw, the ellipse is varied with theshape of the jaw.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be clearlyunderstood by reading the following description of a preferredembodiment thereof with reference to the accompanying drawings, whereinthe same reference symbols in different figures denote correspondingparts, and wherein:

FIG. 1 is a somewhat schematic top plan view showing the principle onwhich the invention is based;

FIG. 2 is a view similar to FIG. 1 but showing some of the componentparts in a different operative position;

FIG. 3 is a somewhat schematic top plan view showing connecting meansfor adjusting the shape of the ellipse along the arc of which the X-raytube and the film are moved together;

FIG. 4 is a part-cut-away perspective view of one embodiment of theinvention, absent the foregoing means for adjusting the shape of theellipse;

FIG. 5 is a part perspective view of the connection between theadjustment means and the basic device;

FIG. 6 is a part top plan view of the latter; and

FIG. 7 is a part side view of the same.

Referring first to FIG. 1, which shows the arrangement on which theinvention is based, there is shown a reference or base 1 having a slot 2formed therein. A pin 4 engages in the slot 2 so as to be slidable alongthe length thereof and is secured to one end of a link or arm 3, theother end of which is pivoted by a pin 5 to one end of a link or arm 6.In the opposite end of the arm 6 there is formed a slot 7 extending asuitable distance along the length of the arm. A pin 8 is fixed on thebase 1 on a straight line with the slot 2, and at a suitable distancefrom one end of the slot 2. The pin 8 engages in the slot 7 formed inthe arm 6 so as to be slidable along the length thereof. A pin 9 ispivotally connected at a suitable position on the arm 6, and by means tobe later illustrated, pivotably supports a relatively rotatable drivemember or arm 10 having a slot 11 formed therein. The previouslymentioned pin 4 slidably engages in this slot 11 as well as the slot 2.

On the straight line between the slot 2 and the pin 8, and at a suitabledistance from the opposite end of the slot 2, there is another pin 12fixed to the base 1. In the embodiment of the invention shown in FIGS.3-7, the position of the pin 12 is variable relative to the pin 8, orthe base 1, as shall be described.

Along the sides of the triangle formed by the straight lines connectingthe pins 8, 9 and 12, an endless flexible band 13 extends, so that asthe band is driven by means to be later illustrated, the pin 9 is movedalong. In practice, rotary members to be later illustrated, such assprocket wheels, are provided on the pins 8, 9 and 12, and the band 13takes the form of an endless chain engaged with the sprocket wheels.With such an arrangement, slip between the pin 9 and the band 13 caneffectively be avoided.

An X-ray tube 21 and a film holder 22 are mounted on the opposite endsof the support arm 10, respectively. The patient is positionedintermediate the X-ray tube and the film holder in such a manner thatthe major axis of an ellipse approximately conforming to the dental archof the patient, coincides or is aligned with the straight lineconnecting the pins 8 and 12, or an extension of the line.

As is easily understood, the sum of the sides of the triangle formed bythe lines connecting the pins 8, 9 and 12, is always the same regardlessof the position of the pin 9 driven by the band 13. If the distancebetween the pins 8 and 12 is fixed, the sum of the distances between thepins 8 and 9, and that between the pins 9 and 12, is constant regardlessof the position of the pin 9. This means that the pin 9 is moved alongthe locus of the ellipse 14 with the positions of the pins 8 and 12 asits foci. As seen, the slot 2 coincides with the major axis of theellipse l4, and in FIG. 1 the arm 10 coincides with the minor axisthereof.

Since the pin 8 slidably engages in the slot 7 of the arm 6, the arm 6can move longitudinally of itself, so that even when the pin 9 is at theabove-mentioned position, the arm 6 can take a desired positioncorresponding to the position of the pin 9. Since the pin exists on theextension of a line connecting the pins 8 and 9, and the arm 3 connectsthe pin 5 and the pin 4, which latter pin is always on the major axis ofthe ellipse 14, the distance between the pins 4 and 5 is kept constantregardless of the positional change of the pin 9. Since the arm connectsthe pins 4 and 9, the arrangement is also such that when the pin 9assumes a position on the minor axis of the ellipse 14, the pin 4assumes a position at the center, that is, the intersection of the majorand minor axes of the ellipse, and the arm 10 coincides with the minoraxis thereof. In other words, the length of the arm 3, and the positionof the pin 4, are so determined that when the pin 9 assumes a positionon the minor axis of the ellipse, the arm 10 coincides with that axis.

Suppose that the pin 9 has been moved by driving the band 13 from theposition of FIG. 1 to that in FIG. 2. At this position, the pin 9 isstill disposed on the ellipse 14, and the distance between the pins 4and 5 remains unchanged. As shown, the arm 10 crosses the ellipse on aline substantially perpendicular to the tangent to the ellipse at theposition of the pin 9. In this case, however, the distance between thepins 4 and 9 changes as the pin 9 is moved. The slots 4, 7 and 11 areprovided to enable smooth movement of the arms 3 and 6 in accordancewith the above-mentioned distance change.

A patient is positioned between the X-ray tube 21 and the film holder22, in such a manner that the major axis of the ellipse corresponding tothe dental arch of the patient, coincides with the major axis of theellipse 14, and the patients face is so directed that his or her dentalarch is in parallel with the right-hand half of the ellipse (as viewedin FIG. 1 or 2). In other words, the patients face is so directed thatX-ray is projected from behind the head. That is to say, the X-ray tubeis moved transversely behind the patients head and the film, before thepatients face, and as the X-ray tube is moved in the above manner, theX-ray beam is projected substantially perpendicularly to the dental archregardless of the position of the X-ray tube. If an X-ray film is placedcircumferentially on the cylindrical wall of the film holder 22, and isrotated about its own axis in synchronism with the movement of the X-raytube, it is possible to take a continuous picture of the dental arch onthe film.

Referring now to the embodiment illustrated in FIG. 4, it will be seenthat the base 1 has a U-shaped or yokelike cross section, and iscomprised of a pair of rounded, spaced, parallel brackets 40 and 42,interconnected by a bight connection 44 therebetween. The

pin 8 extends upright between the brackets, and is fixed to both. Thepin 4 is upstanding on the lower bracket 42, at a point adjacent therounded end 42' thereof; whereas the pin 12 depends from the upperbracket 40, at a point more closely adjacent the rounded end 40 thereof.The arm 10 is slung below the lower bracket, by means of an L-shapedextension 46 upstanding thereon, the outlying end of which has the pin 9pivotally engaged therein. The pin 9 is pivotally upstanding in the arm6 therebelow, and connected with the pin 9, as well as with each of thepins 8 and 12, is a sprocket 48 or other means for carrying the chain 13interconnected among the pins. The chain 13 is driven through the pin 9,by means of a spur gear 50 thereon which is in mesh with a cooperatingspur gear 52 on the shaft 54 of a motor 56 mounted on the horizontal leg46 of the extension.

Also mounted on the extension 46 is a biasing device 58 comprising anelongated rod 59 which is slidably engaged in the vertical leg 46" ofthe extension, and equipped with a roller 60 at the left-hand or inboardend thereof, which engages the rounded end 42 of the lower bracket. Theroller 60 is carried in a sheave block 62, and caged between the blockand the vertical leg 46" of the extension is a coiled spring 64, thebias of which maintains the roller against the edge 42' of the bracket,and urges the arm 10, and the pin 9, in the direction outwardly awayfrom the edge 42' of the bracket.

In the above description, it was assumed that the dental archto bephotographed was similar to the righthand half of the ellipse 14. Dentalarches differ in shape between different persons, however, so that it isnecessary to change the shape of the right-hand half of the ellipse 14to resemble in shape the dental arch of the particular person to bephotographed. Generally speaking, the dental arch of each personresembles more or less an arc of a geometrical ellipse, so that it issufficient to change the eccentricity of the ellipse 14 in accordancewith the shape of the particular dental arch to be photographed. To thisend, either the major or minor axis, or both, must be changed; and tochange them, either the distance between the pins 8 and 12, or the sumof the distance between the pins 8 and 9 and that between the pins 9 and1 2, may be changed. Moreover, the shape of a dental arch is determinedby its width, which in turn approximates the width of the jaw.Therefore, the ellipse 14 may be changed in accordance with the width ofthe jaw of each individual.

FIG. 3 shows an arrangement constructed in accordance with the inventionwherein the ellipse 14 is adjusted by displacing the pin 12 along themajor axis thereof in accordance with the width of the patients jaw. Asseen, when the pin 12 is displaced toward the pin 8, the ellipse 14 hasa shorter major axis and a longer minor axis. Were the pin 12 displacedaway from the pin 8, the ellipse would have a longer major axis and ashorter minor axis. To effect such a relative displacement of the pin12, a screw rod 31 is provided in alignment with the major axis of theellipse, and the pin 12 is not fixed on the base, but is movablerelative thereto. An internally threaded-through bore is formed in thepin 12, transversely of the axis thereof, so that the rod 31 may bethreaded through the bore. As the rod 31 is rotated about its axis, thepin 12 moves along the length of the rod 31, that is, the major axis ofthe ellipse 14, thereby changing its relative position to the pin 8.

A controller 32 controls the rotation of the rod 31. The controller 32includes a motor (not shown) adapted to be rotated an amount determinedby the change in the distance L between a pair of calipers or levers 33and 34. To put it in detail, so long as the distance L remains areference length, the motor does not rotate. If the distance L becomesshorter than the reference length, the motor is rotated in accordancewith the difference between the distance L and the reference length, soas to move the pin 12 rightward in FIG. 3; whereas if the distance Lbecomes longer than the reference length, the motor is accordinglyrotated so as to move the pin 12 leftward. The controller may be sodesigned that a voltage is produced corresponding to the distance Lbetween the two levers 33 and 34, and the voltage is compared with areference voltage so that the difference in voltage may be used to drivethe motor. The construction of such a controller is well known in theart, so that no further explanation should be required.

A patient 35 has his jaw held between the tip ends of the levers 33 and34, so that the distance L is varied with the width of the jaw. It isnot necessary that the jaw be held between the levers, but in fact, anyother portion of the face or head, the width of which is proportional tothe width of the dental arch, may be held between the levers.

In the arrangement of F IG. 3 the pin 12 is automatically moved inaccordance with the distance L. The arrangement may also be such thatthe width of the dental arch is separately measured, and the pin 12 maybe manually moved in accordance with the measured width. Also, insteadof displacing the pin 12, the length of the band 13 may be changed forthe same purpose.

FlGS. 5-7 illustrate one mode of mounting the pin 12. As seen, therounded end 40' of the base 1 has a slot 66 therein, and the pin 12 hasa poll 68 thereon which is slotted at either side to ride on the basewithin the slot 66.

What we claim is:

1. An apparatus for taking a continuous X-ray picture of the dentalarch, comprising: a base; first and second pins fixed on said base at adistance apart from each other; an elongated support member forsupporting an X-ray tube and an X-ray film at the opposite ends thereofrespectively, and having a first slot formed intermediate the lengththereof; a third pin fixed on said support member; a first arm pivotedto said support member by said third pin and having at one end thereof asecond slot in which said first pin slidably engages; a second armhaving one end pivoted to the 0pposite end of said first arm; a thirdslot formed in said base in coincidence with a straight line connectingsaid first and second pins; a fourth pin fixed on the opposite end ofsaid second arm and engaging in both said first and third slots;sprockets on the first, second, and third pins; a loop member endlesslypassing about the sprockets and adapted to be driven so as to drive saidthird pin along the locus of an ellipse; said dental arch beingoperatively disposed intermediate said X-ray tube and film with themajor axis of an ellipse approximating said dental arch coinciding withthe straight line connecting said first and second pins; and meanswhereby at least one of said first and second pins is displaceablerelative to the other along the line connecting said first and secondpins, to vary the eccentricity of the ellipse travelled by the thirdpin.

2. The apparatus of claim 1, further comprising means whereby thedisplaced position of the one pin is determined by the distance betweena pair of levers adapted to engage the jaw of the dental patienttherebetween.

3. In apparatus for recording a continuous X-ray picture of the dentalarch, a fixed reference, a relatively rotatable drive member which iscam connected with the reference and equipped with an X-ray source andan X-ray film holder on opposite sides of the cam connectiontherebetween, a relatively articulated linkage cam connected with thereference and with the drive member at the cam connection between thedrive member and the reference, means forming a pivotal connectionbetween the linkage and the drive member, drive means operable to causethe pivotal connection between the linkage and the drive member to movethrough an elliptical path, and thereby cause the source and the holderto trace coaxial elliptical paths, and means for varying theeccentricity of the elliptical paths of the source and the holder.

4. The apparatus according to claim 3 wherein the drive means includes apower unit and a system of rotary members on the reference and thepivotal connection between the linkage and the drive member,interconnected with one another and with the power unit to be driven inunison by the unit; and wherein one of the rotary members is selectivelyshiftable in relation to the reference to vary the eccentricity of theelliptical path of the pivotal connection between the linkage and thedrive member.

5. The apparatus according to claim 4 further com prising a calipers fordetermining a variable distance, and means operable to shift the onerotary member in relation to the reference, commensurate with thevariation in said distance determined by the calipers.

6. The apparatus according to claim 3 wherein the drive means includes apower unit on the drive member, a rotary member on the pivotalconnection between the linkage and the drive member, driven by the powerunit, a pair of spaced rotary members on the reference, one of which iscoaxial with the cam connection between the linkage and the reference,and a rotary connection between the rotary member on the pivotalconnection between the linkage and the drive member and each of therotary members on the reference, whereby the rotary member on thepivotal connection between the linkage and the drive member is caused totrace an elliptical path as it is driven by the power unit, the otherrotary member on the reference being selectively shiftable in relationto the reference to vary the eccentricity of the elliptical path of therotary member on the pivotal connection between the linkage and thedrive member.

7. The apparatus according to claim 6 wherein the rotary connectiontakes the form of a flexible band interengaged about the respectiverotary members on the reference and the pivotal connection between thelinkage and the drive member.

8. The apparatus according to claim 7 wherein the reference has anarcuate guide thereon, and there are yieldable biasing means interposedbetween the guide and the drive member to maintain tension in the band.

her at the cam connection between the drive member and the reference,means forming a pivotal connection between the linkage and the drivemember, drive means operable to cause the pivotal connection between thelinkage and the drive member to move through an elliptical path, andthereby cause the source and the holder to trace coaxial ellipticalpaths, and means for varying the eccentricity of the elliptical paths ofthe source and the holder.

1. An apparatus for taking a continuous X-ray picture of the dentalarch, comprising: a base; first and second pins fixed on said base at adistance apart from each other; an elongated support member forsupporting an X-ray tube and an X-ray film at the opposite ends thereofrespectively, and having a first slot formed intermediate the lengththereof; a third pin fixed on said support member; a first arm pivotedto said support member by said third pin and having at one end thereof asecond slot in which said first pin slidably engages; a second armhaving one end pivoted to the opposite end of said first arm; a thirdslot formed in said base in coincidence with a straight line connectingsaid first and second pins; a fourth pin fixed on the opposite end ofsaid second arm and engaging in both said first and third slots;sprockets on the first, second, and third pins; a loop member endlesslypassing about the sprockets and adapted to be driven so as to drive saidthird pin along the locus of an ellipse; said dental arch beingoperatively disposed intermediate said X-ray tube and film with themajor axis of an ellipse approximating said dental arch coinciding withthe straight line connecting said first and second pins; and meanswhereby at least one of said first and second pins is displaceablerelative to the other along the line connecting said first and secondpins, to vary the eccentricity of the ellipse travelled by the thirdpin.
 2. The apparatus of claim 1, further comprising means whereby thedisplaced position of the one pin is determined by the distance betweena pair of levers adapted to engage the jaw of the dental patienttherebetween.
 3. In apparatus for recording a continuous X-ray pictureof the dental arch, a fixed reference, a relatively rotatable drivemember which is cam connected with the reference and equipped with anX-ray source and an X-ray film holder on opposite sides of the camconnection therebetween, a relatively articulated linkage cam connectedwith the reference and with the drive member at the cam connectionbetween the drive member and the reference, means forming a pivotalconnection between the linkage and the drive member, drive meansoperable to cause the pivotal connection between the linkage and thedrive member to move through an elliptical path, and thereby cause thesource and the holder to trace coaxial elliptical paths, and means forvarying the eccentricity of the elliptical paths of the source and theholder.
 4. The apparatus according to claim 3 wherein the drive meansincludes a power unit and a system of rotary members on the referenceand the pivotal connection between the linkage and the drive member,interconnected with one another and with the power unit to be driven inunison by the unit; and wherein one of the rotary members is selectivelyshiftable in relation to the reference to vary the eccentricity of theelliptical path of the pivotal connection between the linkage and thedrive member.
 5. The apparatus according to claim 4 furthEr comprising acalipers for determining a variable distance, and means operable toshift the one rotary member in relation to the reference, commensuratewith the variation in said distance determined by the calipers.
 6. Theapparatus according to claim 3 wherein the drive means includes a powerunit on the drive member, a rotary member on the pivotal connectionbetween the linkage and the drive member, driven by the power unit, apair of spaced rotary members on the reference, one of which is coaxialwith the cam connection between the linkage and the reference, and arotary connection between the rotary member on the pivotal connectionbetween the linkage and the drive member and each of the rotary memberson the reference, whereby the rotary member on the pivotal connectionbetween the linkage and the drive member is caused to trace anelliptical path as it is driven by the power unit, the other rotarymember on the reference being selectively shiftable in relation to thereference to vary the eccentricity of the elliptical path of the rotarymember on the pivotal connection between the linkage and the drivemember.
 7. The apparatus according to claim 6 wherein the rotaryconnection takes the form of a flexible band interengaged about therespective rotary members on the reference and the pivotal connectionbetween the linkage and the drive member.
 8. The apparatus according toclaim 7 wherein the reference has an arcuate guide thereon, and thereare yieldable biasing means interposed between the guide and the drivemember to maintain tension in the band.
 9. The apparatus according toclaim 3 wherein the cam connections take the form of pin and slotconnections.
 10. In combination, a fixed reference, a relativelyrotatable drive member which is cam connected with the reference andequipped with an X-ray source and an X-ray film holder on opposite sidesof the cam connection therebetween, a relatively articulated linkage camconnected with the reference and with the drive member at the camconnection between the drive member and the reference, means forming apivotal connection between the linkage and the drive member, drive meansoperable to cause the pivotal connection between the linkage and thedrive member to move through an elliptical path, and thereby cause thesource and the holder to trace coaxial elliptical paths, and means forvarying the eccentricity of the elliptical paths of the source and theholder.